492 Development of Subdural Hematomas According to Size of the Subarachnoid Space in Benign External Hydrocephalus

Abstract

INTRODUCTION: Benign External Hydrocephalus (BEH) is a common condition seen by pediatric neurologists and neurosurgeons in macrocephalic infants. It is accepted that patients with BEH are at increased risk of spontaneous subdural hematoma (SDHs) formation. METHODS: A large retrospective chart review was performed at a single institution for patients 2 years or younger with a diagnosis of BEH by neurology or neurosurgery and head circumference >85th percentile. Demographic data, head circumference, and occurrence of subdural hematoma were extracted. MRIs were reviewed by two neuroradiologists and the SAS size measured. SAS size was graded per the Tucker et al grading system (<5 mm width is grade 0, 5-9 mm is grade 1 and > 10 mm is grade 2) for consistency. RESULTS: Over 2.5 million patients' charts were queried from a single institution and 480 patients met the inclusion criteria. Of that population, 187 children had an MRI of the brain available for review. The prevalence of spontaneous SDH in this BEH population over 25 years was 8.12% (39 patients of 480). The average size of the SAS was 5.86 mm (± 2.29 mm). A majority, 64.7%, had grade 1 SAS. About 39% had ventriculomegaly. There was no significant association between SAS grade and prevalence of SDHs (p = 0.124). SAS size was not significantly different between those with and without SDH (p= 0.402). CONCLUSION: BEH is a common condition seen by pediatric neurologists and neurosurgeons. Infants with BEH are thought to have increased risk of spontaneous SDH formation compared to the general population. A majority of infants had grade 1 SAS. The grade of SAS was not significantly associated with SDH formation and development of SDH was not associated with larger SAS size.